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AMERICAN JOURNAL OF BOTANY 
[Vol. 8, 
because of the difficulty of getting large quantities of material, as Heyl 
points out when he estimates that it takes 6io million grains of ragweed 
pollen to make a gram. 
Table 5. Kammann's {1Q12) Analysis of Rye Pollen (figures indicate percentages) 
Inorganic substances 13.58 
Water 10.18 
Ash 3.4 
Organic substances 86.42 
Alcohol-ether-soluble 3. 
Carbohydrate 25. 
Non-protein nitrogen 18. 
Protein 40. 
Table 6. Koessler's {191 8) Analysis of Ragweed Pollen {figures indicate percentages^ 
Inorganic substances 21.1 
Moisture 10.5 
Ash 10.6 
Organic substances 78.9 
Total reducing sugars after hydrolysis 6.89 
Ether-soluble lipoids 10.3 
Fatty acids after hydrolysis 4.75 
Phytosterol 0.34 
Insoluble in ether but soluble in 95 percent alcohol 12.5 
Extractives, etc., soluble in alcohol (resins) and water 11.5 
Insoluble residue (crude fiber, proteins, etc.) 37-71 
Table 7. Purin Bases and Amino Acids in Pollen 
Kind of Pollen 
Pine. . . . 
Hazel... 
Pine .... 
Ragweed 
Ragweed 
Authority 
Planta, 
1885 
Planta, 
1885 
Kressling, 
1891 
Heyl, 
1917 
Koessler, 
1918 
Purin Bases 
Hypoxanthine 
Guanine 
Hypoxanthine 
Guanine 
Xanthine 
Guanine 
Hypoxanthine 
Amino Acids 
Histidine 
Arginine 
Lysine 
Agmantine 
Arginine 
Histidine 
Cystine 
Lysine 
Percentage 
0.04 
0.15 
0.015 
0.021 
0.085 
not given 
2.13 
2.41 
0.57 
0.97 
Other Physiological Aspects of Pollen in which Enzymes may Play a Part 
In certain flowers there are two kinds of pollen grains, some of which 
produce tubes and others which do not. Miiller (1883, p. 242) first 
distinguished these as " Befruchtungs''- and Bekos ti gun gs'' -pollens, the 
former being the fertile, and the latter the sterile pollen which Miiller 
